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United States Patent |
5,601,167
|
Kinoshita
,   et al.
|
February 11, 1997
|
One-way clutch
Abstract
A one-way includes a drag strip between a retainer and a driver ring to
ensure transmission of rotation of the driver ring to engagement members
such as sprags even when the driver ring is abruptly accelerated or is
driven at a high speed. The drag strip has a sliding main body which,
after assembly of the drag strip in the one-way clutch, is maintained in
contact with the driver ring. The drag strip also has a hanger which
extends at a right angle from at least one of opposite ends of the sliding
main body into an engagement-member-receiving window of the retainer. On a
side edge of the drag strip, where the drag strip is normally maintained
in contact with an edge of the engagement-member-receiving window of the
inner retainer, the drag strip has an engagement portion engageable with
the edge the engagement-member-receiving window. The engagement portion is
located in the same plane as the side edge of the hanger. The hanger is
maintained in engagement with the retainer by the engagement portion.
Inventors:
|
Kinoshita; Yoshio (Shizuoka-ken, JP);
Suzuki; Tatsuo (Shizuoka-ken, JP);
Shirataki; Hirobumi (Shizuoka-ken, JP)
|
Assignee:
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NSK-Warner K.K. (Tokyo, JP)
|
Appl. No.:
|
502127 |
Filed:
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July 13, 1995 |
Foreign Application Priority Data
Current U.S. Class: |
192/45.1; 188/82.8; 192/41A |
Intern'l Class: |
F16D 041/069 |
Field of Search: |
192/45.1,41 A
188/82.8
|
References Cited
U.S. Patent Documents
2912086 | Nov., 1959 | Troendly et al.
| |
3545581 | Dec., 1970 | Kent.
| |
4089395 | May., 1978 | Fogelberg.
| |
5454458 | Oct., 1995 | Ito | 192/45.
|
Foreign Patent Documents |
1-169130 | Jul., 1989 | JP.
| |
Primary Examiner: Pitts; Andrea L.
Attorney, Agent or Firm: Evenson, McKeown, Edwards & Lenahan, P.L.L.C.
Claims
What is claimed is:
1. In a one-way clutch having engagement members for transmitting drive
force from one of an outer ring and an inner ring to the other, an inner
and outer retainers holding said engagement members in place, a clutch
member for selectively maintaining said engagement members in contact with
an annular outer wall of said inner ring and an annular inner wall of said
outer ring, and a drag strip, said engagement members, inner and outer
retainers, clutch member and drag strip being all disposed between said
annular outer wall of said inner ring and said annular inner wall of said
outer ring, the improvement wherein said drag strip comprises:
a sliding main body for being brought into contact with said annular outer
wall of said inner ring, and
a hanger extending at a right angle from at least one of opposite ends of
said sliding main body into an engagement-member-receiving window of said
inner retainer and, on a side edge of said normally maintained in contact
with an edge of said engagement-member-receiving window of said inner
retainer, having an engagement portion engageable with said edge of said
engagement-member-receiving window, said engagement portion being located
in the same plane as said side edge of said hanger, whereby said hanger is
maintained in engagement with said inner retainer by means of said
engagement portion.
2. A one-way clutch according to claim 1, wherein said engagement portion
is chamfered at a corner on a free edge thereof, said corner being on a
side facing said edge of said engagement-member-receiving window of said
inner retainer, so that attachment of said drag strip to said inner
retainer is facilitated.
3. A one-way clutch according to claim 1, wherein said hanger has a curved
profile on a free edge thereof so that attachment of said drag strip to
said inner retainer is facilitated.
4. A one-way clutch according to claim 1, wherein said engagement members
are sprags and said clutch member is a ribbon spring.
5. A one-way clutch according to claim 1, wherein said drag strip is
provided with an additional hanger of the same type as the first-mentioned
hanger at the other end of said sliding main body.
Description
BACKGROUND OF THE INVENTION
(i) Field of the Invention
This invention relates to a one-way clutch having a drag strip or the like.
b) Description o f the Related Art
A sprag-synchronized one-way clutch is constructed inter alia of an outer
ring having an annular inner wall, an inner ring having an outer wall
concentrically disposed in relation to the inner wall, a plurality of
sprags arranged in an annular space formed between these inner and outer
walls, an outer retainer and inner retainer for holding these sprags at
predetermined positions, and a ribbon spring for applying such force as
maintaining the sprags in contact with the outer and inner rings.
In such a one-way clutch, fictional force applying means such as a drag
strip is arranged between a driver ring, for example, the inner ring and
the inner retainer so that rotation of the inner ring can be surely
transmitted to the sprags even when the inner ring is abruptly accelerated
or is driven at a high speed.
This drag strip is attached to the inner retainer the one-way clutch and,
when the inner ring as driver ring is inserted, a central flat strip
portion is flexed to contact the inner ring under predetermined force. The
drag strip therefore transmits drag torque to in the order of the drag
strip, the inner retainer and the sprags so that engagement of the one-way
clutch is ensured while reducing wearing of the sprags.
One example of the construction of a sprag one-way clutch is illustrated in
FIG. 3. A one-way clutch 10 is equipped with sprags 3, which are held by
an outer retainer 4 and an inner retainer 5 both arranged between an outer
ring and an inner ring 2. Designated at numeral 6 is a ribbon spring which
acts to maintain the sprags 3 in contact with the inner and outer rings.
Numeral 20 indicates a drag strip, which is attached to the inner retainer
5 by hangers 23. A sliding main portion 21 is provided with bent portions
22 and is maintained in adequate frictional contact with the inner ring 2
under spring force. When the inner ring 2 idles in a direction indicated
by arrow A, the drag strip 20 accordingly transmits drag torque in the
order of the drag strip 20, the inner retainer 5 and the sprags 3 so that
the sprags 3 are caused to turn in a direction indicated by arrow B. As a
result, the sprags 3 are tilted toward an idling side and the contact
pressure between the sprags 3 and the inner ring 2 is hence lowered. This
can reduce wearing of the sprags 3 upon idling. When the inner ring 2
rotates in the opposite direction, the resulting frictional force which
acts on the drag strip 20 is also reversed in direction. The inner
retainer 5 therefore pushes the sprags 3 into up eight positions, thereby
surely bringing the sprags 3 into full engagement with the inner and outer
rings 2,1.
Only a conventional drag strip 20 and the inner retainer 5 are i
illustrated in FIG. 4. FIG. 5 is a side view of a hanger 23 of the
conventional drag strip, while FIG. 6 is a schematic view illustrating the
state of attachment of the hanger 23 on the inner retainer 5. The hanger
23 is formed integrally with the sliding main body 21 and, when observed
in cross-section together with the sliding main body 21, presents a turned
square U shape. As is depicted in FIG. 6, the hanger 23 is attached to the
inner retainer 5. Incidentally, numeral 51 indicates a sprag window formed
in the inner retainer 5 to accommodate one of the sprags 3 therein.
In the case of such a drag strip, an end portion of the sliding main body
21 hits the inner wall of the inner retainer 5 whenever the one-way clutch
is engaged or disengaged, as shown in FIG. 7. A portion indicated by arrow
a in FIG. 7 is therefore caused to wear out, resulting in occurrence of
corner-to-corner contact between an upper wall of the turned square
U-shaped hanger 23, said upper wall being indicated at letter b, and an
upper wall of the inner retainer 5. This leads to concentration of stress
on a bent portion of the hanger, said bent portion being indicated by
arrow c, so that the drag strip may be broken there.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a one-way clutch having a
drag strip which is substantially free of the above problem.
In one aspect of the present invention, there is thus provided a one-way
clutch having engagement members, such as sprags, for transmitting drive
force from one of an outer ring and an inner ring to the other, an inner
and outer retainers holding said engagement members in place, a clutch
member, such as a ribbon spring, for selectively maintaining said
engagement members in contact with an annular outer wall of said inner
ring and an annular inner wall of said outer ring, and a drag spring. The
engagement members, inner and outer retainers, clutch member and drag
spring are all disposed between said annular outer wall of said inner ring
and said annular inner wall of said outer ring. The drag strip comprises:
a sliding main body for being brought into contact with said annular outer
wall of said inner ring, and
a hanger extending at a right angle from at least one of opposite ends of
said sliding main body into an engagement-member-receiving window of said
inner retainer and, on a side edge normally maintained in contact with an
edge of said engagement-member-receiving window of said inner retainer,
having an engagement portion engageable with said edge of said
engagement-member-receiving window, said engagement portion being located
in the same plane as said side edge of said hanger, whereby said hanger is
maintained in engagement with said inner retainer by means of said
engagement portion.
Owing to the above-described construction of the drag spring employed in
the one-way clutch according to the present invention, the drag spring can
be easily attached to the inner retainer and can avoid breakage at the
portion of the hanger during use.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a drag strip in a one-way clutch according to one
embodiment of the present invention, in which a part of an associated
inner retainer is also shown;
FIG. 2 is a side view of a hanger of the drag strip depicted in FIG. 1;
FIG. 3 is a fragmentary rear view showing the construction of a typical
one-way clutch;
FIG. 4 is a front view of a drag strip in a conventional one-way clutch, in
which a part of an associated inner retainer is also shown;
FIG. 5 is a side view of a hanger of the drag strip depicted in FIG. 4;
FIG. 6 is schematic illustration showing the state of attachment of the
hanger, which is depicted in FIG.5, to an associated inner retainer;
FIG. 7 is a schematic illustration showing a drawback of the conventional
drag strip depicted in FIG. 4;
FIG. 8 is a schematic illustration showing the state of attachment of the
hanger, which is depicted in FIG. 2, to the associated inner retainer;
FIG. 9 shows a first modification of the hanger depicted in FIG. 2;
FIG. 10 shows a second modification of the hanger depicted in FIG. 2;
FIG. 11 shows a third modification of the hanger depicted in FIG. 2;
FIG. 12 shows a fourth modification of the hanger depicted in FIG. 2, said
fourth modification including a curved profile on a free edge of the
hanger;
FIG. 13 shows a fifth modification of the hanger according to the first
modification depicted in FIG. 9, in which the hanger is chamfered;
FIG. 14 illustrates displacement of hangers toward a center of a drag strip
upon assembly of an inner ring; and
FIG. 15 illustrates displacement of hangers away from a center of a drag
strip upon assembly of an inner ring.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENT
Referring first to FIGS. 1 and 2, the drag strip in the one-way clutch
according to the first embodiment of the present invention will be
described. The drag strip is designated by numeral 20 in FIG. 1. The drag
strip 20 comprises a sliding main body 21 and hangers 24 arranged at
opposite end portions of the sliding main body 21, respectively. As these
hangers 24 are identical to each other except for the extending directions
of their engagement portions 25 which will be described subsequently
herein, only one of the hangers 24 will hereinafter be described. The
hanger 24 extends at a right angle from the corresponding end portion of
the sliding main body 21 into a sprag window 51 formed as an
engagement-member-receiving window in the inner retainer 5.
Since the hanger 24 of the drag strip 20 in the one-way clutch according to
the one embodiment of the present invention does not have any top wall, no
corner-to-corner contact takes place between the hanger 24 and the inner
retainer 5 even if the end portion of the sliding main body 21 wears out.
From a side edge of the hanger 24, said side edge being normally maintained
in contact with an edge of the sprag window 51, the engagement portion 25
extends out in an angular direction of the inner retainer 5. The
engagement portion 25 is located in the same plane as the side edge of the
hanger 24. The engagement portion 25 is in engagement with the edge of the
sprag window 51, where by the hanger 24 is maintained in engagement with
the inner retainer 5 by means of the engagement portion 25.
Reference is now had to FIG. 8. As will be described subsequently herein,
the drag strip 20 is in the position indicated by solid lines after the
clutch assembly has been assembled on the inner ring. Before its assembly
on the inner ring, however, the hanger takes the position indicated by
broken lines 24' to maintain the engagement portion 25' in engagement with
the edge of the sprag window 51 so that the drag strip 20 is prevented
from being detached from the inner retainer 5 under the action of the
ribbon spring 6 (see FIG. 3).
In the first embodiment depicted in FIG. 8, an engagement portion 25
extends in a direction away from the drag strip 20 (namely, clockwise as
viewed in FIG. 8). Various modifications of the engagement portion 25 will
hereinafter be described with reference to FIG. 9 to FIG. 13.
In the first modification depicted in FIG. 9, an outer side edge portion
26a of a hanger 26 extending through the sprag window 51 is tilted so that
the tilted outer side edge portion 26a can be brought into engagement with
the edge of the sprag window 51.
In the second modification depicted in FIG. 10, an engagement portion 25 of
a hanger 24 in the sprag window 51 extends in a direction opposite to the
extending direction of the engagement portion 25 in FIG. 8, that is,
toward a center of the drag strip 20.
In the third modification depicted in FIG. 11, a tilted side edge portion
26a of a hanger 26 is arranged on a side opposite to the tilted side edge
portion 26a in FIG. 9, that is, on a side facing toward the center of the
drag strip 20.
In the conventional drag strip 20 shown in FIG. 4 through FIG. 7, the
hanger 23 has a turned square U-shaped cross-section when viewed together
with the corresponding portion of the sliding main body 21. The drag strip
20 is attached to the inner retainer 5 before assembling sprags 3. The
sprags 3 are then assembled. The sprags 3 therefore act as stoppers.
Each hanger 24 or 26 of the drag strip 20 in the one-way clutch according
to the one embodiment of the present invention extends at a right angle
from the sliding main body 21 and hence has an L-shaped cross-section when
viewed together with the corresponding portion of the Sliding main body
21. This configuration of the hanger 24 or 26 permits attachment of the
drag strip 20 to the inner retainer 5 subsequent to assembly on the sprags
3 in the inner retainer 5.
In the fourth modification depicted in FIG. 12, a free edge of a hanger 24,
said free edge being an upper edge as viewed in FIG. 12 and being indicted
by arrow R in the same figure, has a curved profile. In the fifth
modification shogun in FIG. 13, a hanger 26 is chamfered at a portion
indicated by arrow P, namely, at an upper right corner as viewed in FIG.
13.
FIGS. 14 and 15 each illustrates a change in the shape of a drag strip in a
one-way clutch according to the present invention before and after
assembly of the inner ring.
FIG. 14 shows hangers with engagement portions extending away from the drag
strip as shown in FIGS. 8 and 9. A solid line 21 indicates a sliding main
body after its attachment to the inner retainer but before assembly of the
inner ring. The solid line 21 is straight A broken line 21', on the other
hand, indicates the state of the sliding main body after the inner ring
has been assembled. The sliding main body is in an arcuate form so that
the hangers 24 have been displaced toward the center of the drag strip as
indicated by arrows (see FIG. 8).
FIG. 15 illustrates hangers with engagement portions extending the center
of the drag strip as shown in FIGS. 10 and 11. Before assembly of the
inner ring, the sliding main body 21 has been attached to the inner
retainer in such a shape that the sliding main body 21 presents a inwardly
convex arcuate profile as indicated by a solid line. After the inner ring
has been assembled, the sliding main body takes a substantially straight
profile so that the hangers 24 have been displaced away from the drag
strip as indicated by arrows.
In each of these two types of hangers, the hangers are separated from the
edges of the corresponding sprag windows when the sliding surface of the
sliding main body 21 of the drag strip 20 is pressed by,the inner ring 2.
In the first embodiment of the present invention illustrated in FIG. 1, the
drag strip 20 is provided at the opposite ends thereof with the hangers
24, respectively. The drag strip 20 may however be provided with only one
hanger 24 at one of the opposite ends thereof.
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